1. Technical Field of the Invention
The present invention relates to the field of mobile telecommunications and, in particular, to an all Internet Protocol (IP) code division multiple access (CDMA) mobile telecommunications system, and methodology for the implementation thereof.
2. Description of Related Art and Background
The evolution of wireless communication over the past century, since Guglielmo Marconi's 1887 demonstration of radio's ability to provide continuous contact with ships sailing the English Channel, has been remarkable. Since Marconi's discovery, new wireline and wireless communication methods, services and standards have been adopted by people throughout the world. This evolution has been accelerating, particularly over the last ten years, during which the mobile radio communications industry has grown by orders of magnitude, fueled by numerous technological advances that have made portable radio equipment smaller, cheaper and more reliable. The exponential growth of mobile telephony will continue to rise in the coming decades as well, as this wireless network interacts with and eventually overtakes the existing wireline networks.
While the advantages of wireless communications are numerous, the limitations are also clearly defined, most notably the finite bandwidth available for cellular services. While the Federal Communications Commission (FCC) may, from time to time, provide additional bands for cellular services, wireless bandwidth is inherently limited. Thus, the technical challenge is to maximize the utilization of the available capacity, a strategy demonstrated by the dominance of digital cellular over its analog counterpart. Through digitalization of wireless communications, the advantages of multiplexing and voice compression by way of voice coding are achieved, both providing additional channels for a given bandwidth. Although digital multiplexing systems have proven efficient and successful on enormous scales, e.g., the Global System for Mobile Communications (GSM), the drive for increased traffic over a limited bandwidth continues. Most recently, the emergence of code division multiple access (CDMA) has promised to reshape the industry.
CDMA, in general, converts a narrowband modulated signal and spreads it across a much wider bandwidth, e.g., over 1000 times the source bandwidth in some systems, by multiplication of a pseudorandom code sequence, e.g., the well-known Walsh codes. Originally developed for military applications in its simplest form, i.e., frequency hopping, spread spectrum modulation techniques have been used in some American military satellites for over twenty-five years in large part to capitalize on the inherent security offered by spread spectrum transmissions. CDMA has recently emerged as a viable cellular telecommunications modulation scheme, as demonstrated by the numerous commercial CDMA networks now in operation.
Packet data services are not new to the cellular world. GSM, for example, provides packet services through the use of a packet assembler and disassembler (PAD) device, although currently the GSM standard is a circuit-switched architecture. Thus, in order to access a packet-switched data network, e.g., the Internet, a packet assembler and disassembler must transform the asynchronous data streams from GSM to data packages for transmission across a packet data network. In GSM, for example, the packet assembler and disassembler is invoked by command of a mobile services switching center (MSC), which also directs the circuit-switched voice allocations, as is well understood in the telecommunications arts.
Until recently, the prospect of an all Internet Protocol (IP), i.e., substantially all-packetized communications, mobile telecommunications network has been technologically unfeasible. Packet services in cellular telecommunications have heretofore generally been limited to data services where latency issues may have low priority. More specifically, the potential for an all-IP cellular service has been hindered by unacceptable time delays introduced into the delivery of packets, particularly, packets carrying speech data. However, with continuing advances in switching speeds and the continued development of additional cellular infrastructure, for example, packet latency in cellular applications has been reduced to levels where cellular voice IP services are now considered viable. The present invention proposes an architecture for a cellular telecommunications system for providing all services, whether voice or data, according to an IP protocol.
By combining bandwidth efficiencies of a CDMA protocol cellular telecommunications system with all-IP delivery, a more efficient utilization of radio resources is realized, providing advantages over all currently employed cellular systems including analog, Time Division Multiple Access (TDMA) and CDMA.
With the evolution of CDMA as an increasingly viable standard for wireless communications, current CDMA architectures, e.g., the cdma2000 packet data architecture, must adapt to the growing data servicing needs. One difficulty of the current cdma2000 architecture is an inherent tight connection between the conventional circuit-switched (CS) functions or domains and the increasingly important packet-switched functionalities or domains. For example, the cdma2000 architecture requires a Mobile Switching Servicing Center (MSC) for handling not only the typical CS voice calls but also setting up and maintaining packet data session and services. The justification for this tight connection was to reuse, where possible, existing functionality and readily available equipment.
Applicant believes that legacy voice services, i.e., CS-based connections, should evolve towards Internet Protocol (IP) transport, but that this evolution should be independent of that of PS services, enabling the different domains to advance at different paces. A step-wise evolution also enables a network carrier to stop evolving at any step and jump steps to provide enhanced services. As circuit-switching modalities become more outdated and are replaced, all-packet data networks become more and more a reality.
As mentioned, a current CDMA standard is the cdma packet data architecture (TIA PN-4286/3GPP2 PS0001), which embraces IETF protocols, particularly, mobile IP with Authorization Authentication and Accounting (AAA) bundling. With the tight connection between the CS and PS domains in this architecture, it is currently impossible to build a packet data network without a conventional MSC, which, because it is CS-based by its very nature, limits advancements to packet data services throughout the network, thereby hindering progress in the telecommunications and by limiting bandwidth capacity.
In view of the growing demand for and anticipated emergence of an all-packetized cellular system and protocol, there is clearly a need for a methodology addressing these emerging advances, particularly, regarding movement toward an all-IP CDMA implementation. Since most companies would rather not be on the cutting or bleeding edge of technological advances, the methodology should provide a mechanism for supporting legacy equipment, i.e., non-all-IP or voice circuit-switched devices, for a non-bleeding edge conversion to an increasingly packet-switched voice and data protocol and telecommunications network.
It is, therefore, an object of the present invention to provide an economically improved methodology to enable telecommunications system operators to stepwise migrate from conventional circuit-switched networks and mixed circuit-switched and packet data networks to an increasingly predominant packet data switching network.
It is also an object of the present invention to, in addition to evolving a network to packet switching, offer the simultaneous and independent ability to allow the telecommunications systems operators to evolve the voice circuit-switched domain to accommodate local traffic needs.
It is a further object of the present invention to improve upon existing standards e.g., the current cdma2000 architecture, that tightly bind CS-domain functionalities with the PS-domain functionalities, particularly, by routing all communications, whether CS-based voice of PS-based data, through an MSC, the improvements resulting in enhanced efficiencies.